Title: Convection currents (How does the inside of the earth move?)
Lesson Overview During this lesson the class discusses the their results from the past two day inquiry activity. Students then make further observations of convection currents through a class observation. The teacher will connect the information observed and recorded to the learning of convection currents.
Objectives 1. Students will be able to explain how a convection cell works. 2. Students will be able to draw a convection cell. 3. Students will analyze, summarize and discuss evidence relating to convection currents.
Materials Hot plate Water Beakers Glitter Worksheet on convection currents
Links to Resources
Safety Issues
1. Students need to be very aware of the hot liquid and the heat of the hot plate.
2. Students also need to be informed of the liquid being hot and possibly bubbling out of the beaker. For this reason students will need to keep their hot plate on a medium setting only and NOT on high.
3. Students also need to know if they are not following instructions they will promptly be removed from the lab.
Instruction
Opening When class begins ask some groups to share their hypotheses, their data, what they think their data demonstrates, what they can learn from each individual experiment, and the experiment as a whole. Ask questions like how did a change in the density of a substance affect the location of that substance in relation to other substances? What would happen if the substance became less dense than the substances around it? Denser? What can you do to a substance to change its density? (10 min) Learning Activities So in the previous activity we learned it was possible to change the density of a substance to cause movement, but we still need to understand how the earth moves. This next demonstration will help us to understand this. In this demonstration two beakers filled ¾ of the way with water will be used. Both of the beakers will have glitter sprinkled on top. One beaker will be placed on the hot plate, and the other beaker will be placed on the counter as the control. Students will write their observation in their science notebook. Questions: What do you think is causing the glitter to travel in circular paths? Why do you think some glitter is rising while the other glitter is sinking? What could be the difference between the two sections of water containing glitter? What type of change of density causes substances to rise? What factors can cause decrease in density to occur? What is one factor in this experiment that would affect density? So then why is the glitter rising? Sinking?
What is the main difference between the two sections of water—the one that is rising and the one that is sinking? This rising and sinking of water creates currents called convection cells. If the water is moving to the top what causes it to rise? Where did this increase in temperature come from? So when a substance cools it becomes denser and sinks, when the temperature increases it becomes less dense and rises. How does the heated water that rises to the top then become the cooler water that sinks? What must happen to the heated water for it to sink?
Material inside the mantle moves in convection cells. We are going to use our knowledge of convection cells from our demonstration to help us understand the convection cells in the mantle. In our demonstration what causes the molecules to start rising? Where did this increase in temperature come from? Where does it come from in the earth? (35 min)
Closing In closing the class will discuss how the knowledge of convection currents can be applied to real world situations. Where is it warmer in a two story building? Where do you want the heat vents in your home? Students will be assigned for homework to draw a convection cell. The worksheet will be given to them and we will meet in class the next day. (10 min)
Assessment Students will be assessed on their model of the convection cell.
Homework Worksheet of the model of the convection cell
Unit: Plate Tectonics
Title: Convection currents (How does the inside of the earth move?)
Lesson Overview
During this lesson the class discusses the their results from the past two day inquiry activity. Students then make further observations of convection currents through a class observation. The teacher will connect the information observed and recorded to the learning of convection currents.
Objectives
1. Students will be able to explain how a convection cell works.
2. Students will be able to draw a convection cell.
3. Students will analyze, summarize and discuss evidence relating to convection currents.
Materials
Hot plate
Water
Beakers
Glitter
Worksheet on convection currents
Links to Resources
Safety Issues
Instruction
Opening
When class begins ask some groups to share their hypotheses, their data, what they think their data demonstrates, what they can learn from each individual experiment, and the experiment as a whole. Ask questions like how did a change in the density of a substance affect the location of that substance in relation to other substances? What would happen if the substance became less dense than the substances around it? Denser? What can you do to a substance to change its density?
(10 min)
Learning Activities
So in the previous activity we learned it was possible to change the density of a substance to cause movement, but we still need to understand how the earth moves. This next demonstration will help us to understand this. In this demonstration two beakers filled ¾ of the way with water will be used. Both of the beakers will have glitter sprinkled on top. One beaker will be placed on the hot plate, and the other beaker will be placed on the counter as the control. Students will write their observation in their science notebook. Questions: What do you think is causing the glitter to travel in circular paths? Why do you think some glitter is rising while the other glitter is sinking? What could be the difference between the two sections of water containing glitter? What type of change of density causes substances to rise? What factors can cause decrease in density to occur? What is one factor in this experiment that would affect density? So then why is the glitter rising? Sinking?
What is the main difference between the two sections of water—the one that is rising and the one that is sinking? This rising and sinking of water creates currents called convection cells. If the water is moving to the top what causes it to rise? Where did this increase in temperature come from? So when a substance cools it becomes denser and sinks, when the temperature increases it becomes less dense and rises. How does the heated water that rises to the top then become the cooler water that sinks? What must happen to the heated water for it to sink?
Material inside the mantle moves in convection cells. We are going to use our knowledge of convection cells from our demonstration to help us understand the convection cells in the mantle. In our demonstration what causes the molecules to start rising? Where did this increase in temperature come from? Where does it come from in the earth?
(35 min)
Closing
In closing the class will discuss how the knowledge of convection currents can be applied to real world situations. Where is it warmer in a two story building? Where do you want the heat vents in your home? Students will be assigned for homework to draw a convection cell. The worksheet will be given to them and we will meet in class the next day.
(10 min)
Assessment
Students will be assessed on their model of the convection cell.
Homework
Worksheet of the model of the convection cell
Additional Notes
http://astroventure.arc.nasa.gov/teachers/pdf/AV-Geolesson-4.pdf
Lab modified from this source.